Sewing machine with removable stitching plate



References Cited UNITED STATES PATENTS United States Patent Gunter MeierWeingarten, Germany 0 6 2 l 2 1 ll mm w mbmww mnm b mm u ASMG

7 GA 0.. de N. mm m m pn ms AFPA 11:1] 253 2247 [iii PrimaryExaminer-Jordan Franklin Assistant Examiner-George H. KrizmanichAttorney Karl Rath ABSTRACT: The stitching plate of a sewing machine isslidably supported, between an operative and an inoperative sewingtable, by shoulders extendte edges of a rectangular opening in untinglugs, extending from the o adjoining said shoulders, are ada Tum W0 mmmOD lm f erh m mmw m ."nrfa e a O h pA nt il a f m e y o ol nb enndimmewbzm uhouh.n sssb 0 00 .mwPmPPw a corporation of Germany 32 PriorityDec.l8,l967

Germany 31 N0.P30589 s41 SEWING MACHINE WITH REMOVABLE and flush thepted esses of said edges in the inoperative tly lock, in the operativespondling abutments of the STITCHING PLATE 9 Claims, 3 Drawing Figs.

[51] Int. [50] FieldofSearch......

, plate upon the sewing table.

SEWING MACHINE WITH REMOVABLE STI'ICIIING PLATE The present inventionrelates to sewing machines, more particularly to a removable stitchingplate mounted within an.

opening of the cloth plate or sewing table of a machine between thereciprocatory needle and lower stitch-forming tools (loop-taker), saidplate being provided in a known manner with apertures for the passage ofthe needle and work feed dog during operation. a

As is well known, sewing dust or particles given off by the sewingmaterial accumulate below the stitching plate during operation and mustbe removed from time to time, to ensure a disturbance free operation ofthe lower stitch-forming tools (loop-taker) mounted underneath thestitching plate. For this purpose, it is customary to removably mountthe stitching According to conventional practice, the stitching plate issecured by the aid of a pair of countersunk screws. This manner ofmounting has been found impractical, because it requires a special tool(screwdriver) for the tightening and loosening of the screws, while therepeated unscrewing and reinsertion of the screws may lead to an earlydamage of the screw threads and the screwdriver slits in the headsthereof. As a consequence, the screws may no longer properly fit in thedepressions of the stitching plate, whereby to result in damage to thework or sewing material being operated on, as well as in other defectsand drawbacks. Besides, screwing and unscrewing of the plates is bothtime-consuming and troublesome to the ordinary sewing machine user oroperator.

In order to obviate the foregoing disadvantages, it has already beenproposed to provide the stitching plate with special projections adaptedto resiliently interlock with cooperating projections of the cloth plateor stitching table against the action of intervening locking springs.This manner of resiliently.

supporting the stitching plate involves the dangerof; vibration of theplates during thehigher sewing speeds of the machine. Besides,difficulties are experienced in withdrawing the plates from theoperative to the inoperative positionagainst the action of the lockingsprings. i It has furtherrnorefbeen proposed-,in an effort to overcomethe previous difficulties, to provide a supporting ledge at one end ofthe stitching plate adapted to engage aslot inthe cloth plate or sewingtable. The opposite end of the plate is secured by means of a pivotedlocking spring or clasp operated by an eccentric control.Such'arrangements are relatively bulky and unsuited for certain types ofmachines, while having the further drawback that the locking elementmustbe disposed underneath the stitching plate or sewing table.

Accordingly,'an iinportant'object of the present invention is theprovision of an improved removable stitching plate for sewing machinesof the referred to type which may be firmly locked in the operativeposition without requiring any special securing means; which requires nospecial tools for its removal and mounting; which can be removed andreinserted instantly and readily by mounting means accessible from theupper side With the foregoing objects in view, the invention, accordingto one of its aspects, involves generally the provision of a stitchingplate for a sewing machine of the referred to type slidably supported,between an inoperative and an operative position and flush with thecloth plate or sewing table of the machine, by apair of shoulders uponthe opposite edges of a rectangular opening of said cloth plate ortable. In order to removably support the stitching plate, the same isprovided with mounting lugs projecting from the opposite edges thereofadjoining said shoulders, said lugs being adapted to loosely fit, in theinoperative position of the plate, suitable recesses in the edges ofsaid opening, to enable easy insertion and withdrawal, and said lugsadapted, in theoperative position of said plate, to resiliently engageor look with corresponding ledges or abutments of said tabledisposedwithin said edges and adjoining said recesses.

,- According to a preferred embodiment, the mounting lugs in theoperative position of the stitching plate are displaced fromthe'adjoining i'ecessesby a distance equal to the width of the lugs,whereby. to result in a minimum distance or movement between theoperative and inoperative positions of the plate. The stitching plate isfurthermore provided in a known manner with a suitable aperture, toenable the passage of the needlein its operative position, and where afour-motion feed dog is provided, a further oblong aperture being havinga length in excess of the feed stroke or total advance movement of saiddog, is provided, to enable ready passage of the dog during'operation.In the latter case and the preferred embodiment mentioned, thedifference between the length of the oblong aperture and the length ofthe feed dog is ad vantageously in excess of the width of the mountinglugs, to

ensure readyoperation of the stitching plate, in the starting positionofthe quadrilateral movement of the feed dog, substantially withoutobstruction by said dog.

According to an especially advantageous construction, the lugs projectfrom the edges of the stitching plate at an angle in the downwarddirection and the cloth plate is formed with corresponding inclinedabutment surfaces or ledges, to result in a firm resilient yet easilyreleasable locking engagement in the operativeposition of the plate, ina manner as will become v further apparent as the description proceedsin reference to the drawing According to an improved feature,,tominimize operating noise, the stitching plate is removably mounted in aseparate intermediate or damping plate of elastic material which is, inturn, secured in an opening of the sewing table or cloth plate of themachine, and the stitching plate may be further locked or arrested inits operative position by means of an auxiliary locking plate or slidemounted in said table. I

The mounting of the stitching plate in a separate intermediatesupporting plate, being secured to an opening in the sewing table with asufficient play or, clearance, has the added advantage of enabling aready alignment of the plate with the of the sewing table; and which isboth simple in construction and suitable for ready structuralincorporation in conventional sewing machines.

The invention, both as the foregoing and ancillary objects as well asnovel aspects thereof, will be better understood from the followingdetailed description of a preferred practical embodiment, taken inconjunctionwith the accompanying drawing the stitching plate in thelocked or operative position.

Like reference numerals denote like parts in the different viewsofthedrawing. a

mean position of the needle. This in turn enables the parts to befabricated with less stringent tolerance requirements, compared withconventional practice and manufacturing methods.

Referring more particularly. to the drawing, FIG. 1, the nuthem! 1denotes the cloth plate or sewing table of a conventional sewing machinefrom which extends the overhanging arm 2 terminating in a head withinwhich is mounted the reciprocating needle, bar 9 carrying a needle 10.Item 4 denotes an intermediate supporting plate of elastic material,

such as a suitable synthetic plastic, being supported by the ledges 3 ofan opening in the table 1 and secured by means of screws 5, FIG. 2, andserving in turn as a support for the stitching plate 7 of the machineslidably mounted in a rectangular opening 6 of the plate 4, FIGS. 2; and3. As more clearly seen from thelatter, two opposite edges of theU-shaped opening or recess. 6 are provided with throughgoing shoulders6' a slidably supporting the plate 7 between an operative and aninoperative or retracted position, in cooperation with a slide 17mounted flush with the table 1 and forming with the recess 6 arectangular opening of variable width in a manner as will become furtherapparent as the description proceeds.

As further shown by FIG. 2, the stitching plate 7 has a first aperture8, to enable passage of the needle 10 during operation for cooperationwith the lower stitch-forming tools (not shown), to produce lockstitchesin the work being operated on in a manner well known. Where a lower feeddog 12 is provided, operated according to the well known four-motionprinciple and mounted below the plate 7, the latter has a furtheropening, or pair of openings, 11, to enable passage of the dog duringoperation.

The stitching plate 7, according to the improved construction, has apair of outwardly projecting mounting lugs 13 disposed on the oppositesides thereof adjoining said shoulders, said lugs adapted to resilientlyengage, in the operative position of the plate shown in the drawing,corresponding ledges or abutments 14 in the opening 6 of theintermediate plate 4, whereby to firmly resiliently lock the stitchingplate in the operative position with the cloth plate, or intennediateplate 7 in the example shown, by virtue of the inherent elasticity ofthe materials.

For manufacturing reasons, the stitching plate 7 is formed with cuts 15extending laterally of the lugs 13 and, in order to enable a readyremoval 'from and reinsertion in the intermediate plate 4, the opening 6in the-plate 4 is formed with lateral recesses 16 in the opposite edgesthereof adjoining the lugs 13, said lugs being displaced, in theoperative position of the plate, from the recesses 16 by a predetermineddistance being less than the difference between the length of theaperture 11 and the length of the feed dog 12, for the purpose aspointed out hereinbefore. The difference between the length of theaperture 11 and the length of the dog 12 slightly exceeds the maximumoperating stroke of the dog in accordance with conventional practice. Acover plate 17 sliding upon the ledges of the opening serves to lockplate 7 in the operative position.

According to an especially advantageous construction, the stroke ordisplacement of the plate 7 from its inoperative position to itsoperative position, and vice versa, or maximum displacement of the lugs13 from the recesses 16 in the operative position of the plate, is equalto the width of the lugs, whereby to ensure a maximum locking effectwith a minimum operat ing stroke or displacement. In other words, thewidth of the recesses 16 is slightly in excess of the width of the lugs13, whereby to provide a loose fit of the lugs within the recesses inthe inoperative position of the plate 7.

As can be clearly seen, the plate 7 may be removed and reinsertedwithout any special tools by simply displacing the same from itsoperative position shown to the inoperative position with the lugs 13loosely fitting the recesses 16. Reinsertion is then effected in reversesequence, as will be further described in the following.

According to a modified construction, the lugs 13 may be offset, toextend in a direction parallel to the plane of the plate 7 and tointerlock with corresponding ledges upon the edges of the opening 6 inthe plate 4. Besides, instead of arranging the lugs 13 on the oppositeedges of the plate 7, they may be disposed on the opposite sides of theapertures 11 for cooperation with suitable complementary lockingelements or abutments extending from the intermediate plate 4 or table1, respectively.

In use, in order to effect the removal of the stitching plate 7 from itsoperative position shown, the sewing machine is arrested ,with theneedle in the up-position corresponding to the feed dog being in thestarting position of its quadrilateral feed movement, that is, aposition adjoining the lower edge of the apertures 11. This position ismost favorable for the safe removal and reinsertion of the stitchingplate. In order to remove the plate, the locking slide 17 is at firstsufficiently withdrawn in the rearward direction, whereupon plate 7 isdisplaced in the same direction until the lugs 13 are positioned in therecesses 16, this operation being facilitated by the roughened grippingsurfaces 18 upon the upper surface of the stitching plate. The lattermay then be removed by withdrawalin the upward direction, to provideready access to the lower stitch-forming tools for cleaning and thecarrying out of adjustments or repairs.

Reinsertion of the stitching plate 7 is effected in reverse sequence byat first applying the same to the opening 6 with the lugs 13 looselyfitting the recesses 16 and subsequently displacing it in .the forwarddirection until the lugs engage the abutments 14, to firmly lock theplate with the table 1 or intermediate plate 4, respectively.

In the foregoing the invention has been described in reference to aspecific exemplary device. It will be understood, however, thatvariations and modifications, as well as the substitution of equivalentparts and elements for those shown herein for-illustration, may be madewithout departing from the broader scope and spirit of the invention.The specification and drawing are accordingly to be regarded in anillustrative rather than in a restrictive sense.

I claim:

1. A sewing machine comprising in combination:

I. a sewing table consisting at least in part of resilient materialhaving a U-shaped opening formed therein and a slide mounted flush withsaid table and having an edge forming a rectangular opening with saidU-shaped opening, the opposite edges of said U-shaped opening beingprovided with recesses;

2. an overhanging arm extending from said table and terminating in ahead carrying a reciprocatory needle;

3. shoulders extending along the opposite edges of said U- shapedopening;

4. a removable stitching plate slidably supported by said shouldersflush with said table, to enable operation thereof between an operativeand a retracted position;

5. a four-motion feed dog below said plate;

6. said stitching plate having a first aperture, to enable passage ofsaid needle, and a second aperture, to enable passage of said feed dog,during a stitching cycle in the operative position of said plate;

7. a pair of mounting lugs extending from the opposite edges of saidplate adjoining said shoulders;

8. a pair of abutments upon said table adjoining said recesses and saidshoulders; and

9. said lugs loosely fitting said recesses, in the retracted position ofsaid plate and resiliently locking, by virtue of the resiliency of thematerial, with said abutments in the operative position of said plate.

2. In a sewing machine as claimed in claim 1, said recesses having awidth slightly in excess of the width of said lugs, and said lugs beingdisplaced, in the operative position of said plate, from the adjoiningrecesses by a distance substantially equaling the width of said lugs. v

3. In a sewing machine as claimed in claim 1, said second aperture beingparallel to said shoulders and having a length in excess of the lengthof said dog, and the stroke of displacement of said stitching platebetween its operative and its retracted positions being less than thedifference between the length of said second aperture andthe length ofsaid dog.

4. In a sewing machine as claimed in claim 1, said second aperture beingparallel to said shoulders and having a length in excess of the lengthof said dog, said recesses having a width slightly in excess of thewidth of said lugs, said lugs being displaced in the operative positionof said stitching plate, from the adjoining recesses by a distancesubstantially equal to the width thereof, and the width of said lugsbeing less than the difference between the length of said secondaperture and the length of said dog.

5. In a sewing machine as claimed in claim 1, wherein said part ofresilient material is an intermediate plate mounted in said table.

6. In a sewing machine as claimed in claim 1, wherein said lugs andabutments extend in a downwardly and an outwardly direction from saidstitching plate and are in resilient locking engagement in the operativeposition of said plate.

7. A sewing machine comprising in combination:

1. a sewing table consisting at least in part of resilient material andhaving a U-shapekl opening and a slide mounted flush with said table andhaving an edge forming a rectangular opening of variable width with saidU- shaped opening, the opposite edges of said U-shaped opening providedwith recesses;

2. an overhanging arm extending from said table and terminating in ahead carrying a reciprocatory needle;

3. shoulders extending along the opposite edges of said first U-shapedopening;

4. a stitching plate slidably supported by said shoulders flush withsaid table, to enable operation thereof between an operative and aretracted position, said plate having an aperture to enable passage ofsaid needle in the operative position,

5. a pair of mounting lugs extending from the opposite edges of saidplate adjoining said shoulders; I 6. a pair of abutments upon said tableadjoining said recesses and said shoulders; and t 7. said lugs looselyfitting said recesses in the retracted position of said plate andresilientlylocking, by virtue of the resiliency of the materials, withsaid abutments in the table is formed with oblique abutments resilientlyengaged by said lugs in the operative position of said plate.

